This review discusses the application of earth-abundant single-atom catalysts (SACs) in electrochemical energy storage and conversion technologies. The authors highlight the importance of SACs in addressing the challenges posed by the increasing energy consumption and the scarcity of rare metal elements used in traditional catalysts. The review covers various electrochemical processes, including lithium-ion batteries, metal-air batteries, metal-sulfur batteries, supercapacitors, and electrochemical reduction of carbon dioxide (CO2). It also delves into the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and nitrogen reduction reaction (NRR). The coordination, active sites, and mechanistic aspects of transition metal SACs are analyzed for two-electron and four-electron reaction pathways. The review emphasizes the potential of earth-abundant SACs in enhancing the performance of these technologies, particularly in terms of energy efficiency, safety, and sustainability. The authors also discuss the challenges and future directions for the development of SACs, including scale-up synthesis, high-value product production, and high energy efficiency.This review discusses the application of earth-abundant single-atom catalysts (SACs) in electrochemical energy storage and conversion technologies. The authors highlight the importance of SACs in addressing the challenges posed by the increasing energy consumption and the scarcity of rare metal elements used in traditional catalysts. The review covers various electrochemical processes, including lithium-ion batteries, metal-air batteries, metal-sulfur batteries, supercapacitors, and electrochemical reduction of carbon dioxide (CO2). It also delves into the oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and nitrogen reduction reaction (NRR). The coordination, active sites, and mechanistic aspects of transition metal SACs are analyzed for two-electron and four-electron reaction pathways. The review emphasizes the potential of earth-abundant SACs in enhancing the performance of these technologies, particularly in terms of energy efficiency, safety, and sustainability. The authors also discuss the challenges and future directions for the development of SACs, including scale-up synthesis, high-value product production, and high energy efficiency.